Serpentine type evaporator

ABSTRACT

In a serpentine type evaporator comprising a serpentine tube provided therein with a plurality of coolant conduits and corrugated in a zigzag pattern, fins interposed between opposed outer surfaces of said serpentine tube, an inlet side header pipe connected to one end of said serpentine tube so as to communicate with said coolant conduits, and an outlet side header pipe connected to the other end of said serpentine tube so as to communicate with said coolant conduits, the improvement in a projection disposed within the outlet side header pipe.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a serpentine type evaporator for use in aspace cooling cycle such as in an automotive air-conditioning system,and more particularly to improvements in and concerning a header pipe onthe outlet side of the evaporator.

2. Description of Prior Art

Generally, the cooler unit of the automotive air-conditioning systemincorporates therein an evaporator which forms part of the space coolingcycle.

Among the conventional evaporators of this class is counted a serpentinetype evaporator constructed as shown in FIG. 1. The serpentine typeevaporator comprises a serpentine tube 1 of a flat cross sectioncontaining a plurality of coolant conduits 2 and corrugated in a zigzagpattern, fins f interposed between each pair of opposed outer surfaces 3of the serpentine tube 1, and an inlet side header pipe 4 and an outletside header pipe 5 connected to the opposite ends of the serpentine tube1 in such a manner that their interiors communicate with the interiorsof the group of coolant conduits 2. Through the inlet side header pipe4, the coolant which has been given decreased pressure and rendered moresusceptible to evporation in an expansion valve flows into the group ofcoolant conduits 2 in the serpentine tube 1. During the travel throughthe group of coolant conduits 2 shaped in a smimlarly corrugated form,the coolant deprives the air flowing between the fins f of heat andevaporates, with the result that the heat of this evaporation cools theair. The gaseous coolant resulting from the evaporation is forwardedthrough the outlet side header pipes 5 into a compressor which is notshown in the diagram.

The serpentine type evaporator by nature is disposed to send offvibratory noise, though feebly, while in operation. Our investigationinto the cause for this noise has uncovered the fact that at the timethe coolant spurts from the coolant conduits 2 of the serpentine tube 1into the outlet side header pipe 5, as illustrated in FIGS. 2 and 3,edge noise occurs in the neighborhood of E portion of the tube outletend and standing current A occurs in the neighborhood of the closed endof the outlet side header pipe 5. Owing to this standing current A, thenoise is generated within the outlet side header pipe of the shapedtube 1. Particularly in the case of automobiles of latest models, sincetheir interiors are kept in deep silence by use of tight seals, it isdesirable that the noise of the cooler unit including the evaporatorwhich is installed in the automobile interior should be precluded at allcost.

An object of this invention, therefore, is to provide an improvedserpentine type evaporator.

Another object of this invention is to provide a serpentine typeevaporator adapted to curb the occurence of the standing current withinthe outlet side header pipe and consequently prevent the occurence ofthe resonance noise.

Yet another object of this invention is to provide an improvedserpentine type evaporator to be incorporated in the space cooling cycleof the air-conditioning system as in the automobile.

SUMMARY OF THE INVENTION

The objects described above are accomplished by an improvement in aserpentine type evaporator comprising a serpentine tube provided thereinwith a plurality of coolant conduits and corrugated in a zigzag pattern,fins interposed between opposed outer surfaces of the serpentine tube,an inlet side header pipe connected to one end of the serpentine tube soas to communicate with the coolant conduits, and an outlet side headerpipe connected to the other end of the serpentine tube so as tocommunicate with the coolant conduits, which improvement is a projectiondisposed within the outlet side header pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a geneal serpentine type evaporator,

FIG. 2 is a cross sectional view illustrating the essential part of aconventional serpentine type evaporator,

FIG. 3 is a cross-sectional view taken along the line III--III in thediagram of FIG. 2,

FIG. 4 is a cross-sectional view of the essential part of a typicalserpentine type evaporator of this invention, and

FIG. 5 is a cross-sectional view taken along the line V--V in thediagram of FIG. 4.

PREFERRED EMBODIMENT OF THE INVENTION

Now, one embodiment of this invention will be described below withreference to the accompanying drawing. FIGS. 4 and 5 are a longitudinalcross section and a lateral cross section, respectively, illustrating anoutlet side header pipe and its vicinity in the serpentine typeevaporator of the present invention.

In the serpentine type evaporator which, as illustrated in FIG. 1,comprises a serpentine tube provided therein with a plurality of coolantconduits and corrugated in a zigzag pattern, fins interposed betweenopposed outer surfaces of the serpentine tube, an inlet side header pipeconnected to one end of the serpentine tube so as to communicate withthe coolant conduits, and an outlet side header pipe connected to theother end of the serpentine tube so as to communicate with the coolantconduits, for example, this invention provides the improvement whichcomprises a closing end plate 16 fitted to one end of the aforementionedoutlet side header pipe 15 to close the end mentioned above and aprojection 17 formed on the aforementioned closing end plate 16 andextended in the axial direction of the aforementioned outlet side headerpipe 15. This projection 17 may be a solid body or a hollow body.Although this projection is desired to be disposed so that the axisthereof will coincide with the axis of the aforementioned outlet sideheader pipe 15, these two axes may deviate slightly from each other. Thelength of this projection 17 may be such that the leading end of theprojection will reach the middle part of the entire length of the outletside header pipe 15. Otherwise, it may be shorter as illustrated in FIG.4. Generally, the length is about 3 to 42%, preferably about 3 to 20%,of the entire length of the outlet side header pipe 15. The diameter ofthe projection 17 is 5 to 50%, preferably 20 to 30%, of the insidediameter of the outlet side header pipe 15. Although the cross sectionof the projection 17 is desired to be circular, it may be elliptical,octagonal or hexagonal.

In the construction described above, when the coolant flows from thecoolant conduits of the serpentine tube 11 into the outlet side headerpipe 15, the projection 17 curbs the occurrence of standing current.Consequently, the vibration of the edge portion of the terminal of theserpentine tube 11 caused by the standing current ceases to exist andthe occurrrence of resonance noise is prevented.

Since the serpentine type evaporator of the present invention isprovided inside the outlet side header pipe with the projection, itprevents the occurrence of resonance noise. In a vehicle incorporatingan automotive air-conditioning system, for example, the improved shapedtube evaporator of this invention prevents occurrence of noise withinthe vehicle interior.

What is claimed is:
 1. In a serpentine type evaporator comprising aserpentine tube provided therein with a plurality of coolant conduitsand corrugated in a zigzag pattern, fins interposed between opposedouter surfaces of said serpentine tube, an inlet side header pipeconnected to one end of said serpentine tube so as to communicate withsaid coolant conduits, and an outlet side header pipe connected to theother end of said serpentine tube so as to communicate with said coolantconduits, said outlet side header pipe being essentially normal to saidserpentine tube and having one end closed, whereby the coolantdischarged from said serpentine tube is directed laterally away fromsaid closed end, the improvement which comprises;means disposed withinthe outlet side header pipe which prevents the formation of a standingcurrent in the neighborhood of the closed end.
 2. A serpentine typeevaporator according to claim 1, wherein said projection is extended inthe axial direction of said outlet side header pipe.
 3. A serpentinetype evaporator according to claim 2, wherein said projection isdisposed coaxially with said oulet side header pipe.
 4. A serpentinetype evaporator according to claim 2, wherein the length of saidprojection is 3 to 20% of the entire length of said outlet side headerpipe.
 5. A serpentine type evaporator according to claim 2, wherein thecross section of said projection is in a circular shape.
 6. A serpentinetype evaporator according to claim 2, wherein the diameter of saidprojection is 20 to 30% of the inside diameter of said outlet sideheader pipe.
 7. A serpentine type evaporator according to claim 1,wherein said means comprises a projection within the outlet side headerpipe in the neighborhood of the closed end.